【作者】 李红杰；

【导师】 逯忠斌；

【作者基本信息】 吉林农业大学 ， 农药学， 2008， 硕士

【摘要】 吡蚜酮是一种选择性杀虫剂,基本结构是嘧啶偶氮甲碱。蔬菜、园艺作物、棉花、大田作物、落叶果树和柑橘上的敏感和抗性蚜虫、粉虱摄食吡蚜酮处理过的植物汁液后,停止取食直至饿死。最近,美国环境保护署认为吡蚜酮有致癌作用的可能性,为了食品和环境的安全,需要一些简单和可靠的残留分析方法检测吡蚜酮。本文对吡蚜酮在稻田水、土和水稻植株中的分析方法,25%吡蚜酮可湿性粒剂在稻田水、土和水稻植株中的残留动态以及在收获期水稻和土壤中最终残留量和吡蚜酮的光降解动态进行了研究。土壤样品采用甲醇/水（8/2）和1%氨水提取,用二氯甲烷萃取,经无水硫酸钠脱水,旋转蒸发,氮吹干,甲醇定容,液相色谱仪测定。水稻植株用乙腈匀浆提取,乙酸-乙酸胺缓冲溶液溶解蒸发后残渣,用二氯甲烷萃取,无水硫酸钠脱水,蒸发至干,用甲醇定容,液相色谱仪测定。糙米、稻壳样品提取同土壤样品,净化同植株样品。水样用二氯甲烷萃取,过无水硫酸钠脱水,蒸发至干,用甲醇定容,液相色谱仪测定。采用安捷伦1100高效液相色谱,DIAMONSIL-C₁₈反相色谱柱（20cm×4.6mm）,V（甲醇）/V（水）=30/70为流动相进行分析。方法的添加浓度分别为0.02mg·kg^-1、0.50mg·kg^-1和1.00mg·kg^-1,平均回收率在82.5%～98.2%之间,变异系数在1.2%～6.3%之间,回收率均大于80%,符合残留分析要求。土壤,植株、糙米、稻壳,水样实际测得最低检出浓度分别为0.0012mg·kg^-1,0.005mg·kg^-1,0.003mg·kg^-1。通过田间试验和高效液相色谱分析技术,研究了25%吡蚜酮可湿性粒剂在稻田水、土和水稻植株中的残留动态以及在收获期水稻和土壤中最终残留量。结果表明,吡蚜酮在稻田水中的降解半衰期为0.19～0.21d,土壤中的降解半衰期为3.5～4.7d,水稻植株中的降解半衰期为0.51～0.53d。吡蚜酮在稻田水、土和水稻植株中的降解符合一级化学反应动力学方程。在水稻生长期喷施一次,按推荐剂量300g·hm^-2和二倍剂量600g·hm^-2施用25%吡蚜酮可湿性粒剂,在收获期土壤、植株、糙米和稻壳中均未检出。测定结果表明,吡蚜酮属于易降解农药(T_1/2＜30d)。在水稻田使用25%吡蚜酮可湿性粒剂时,建议按推荐剂量300g·hm^-2施药一次,水稻上最大残留限量值MRL暂定为0.02mg·kg^-1。在吡蚜酮的光降解实验中,应用500W的中压汞灯并选取了不同浓度、不同pH的吡蚜酮在同一温度和光照条件下进行光降解实验,另外还分析了在紫外灯照射下土壤中吡蚜酮的降解动态。经分析后得到结论:低浓度的吡蚜酮比高浓度的吡蚜酮降解快;低pH比高pH条件下的吡蚜酮降解快;在500W中压汞灯照射下的土壤中吡蚜酮的降解速率明显比在日光的照射下要快,它的降解方程为:C=5.7478e^-0.3887t,半衰期为1.8h。更多还原

【Abstract】 Pymetrozine is a novel selective insecticide.The basic structure is pyridine azomethine.It is effective as a powerful anti-feedant against sucking pests such as aphids,tobacco whiteflies and plant hoppers on a wide range of field,fruit and ornamental crops,provoking a feeding stop and subsequent starvation to death. Recently,the US Environmental Protection Agency（EPA） has classified pymetrozine as a "likely" human carcinogen because two types of（liver benign hepatoma and/or carcinoma） tumors occurred in rat and mouse （male or female） in some studies.For food and environment safety,there is a particular need for simple and reliable analysis method for the determination of it.This text research the analytic method of pymetrozine residue in soil,seedlings and paddy water,determined the residue dynamic and ultimately residue of 25% pymetrozine in soil and rice plant,and had a series of research to study the photodegradation of pymetrozine.Soil samples were extracted with v（methanol）/v（water）=8/2 and 1%ammonium hydroxide,then liquid-liquid partition with dichloromethane;Plant samples are extracted with acetonitrile and anhydrous sodium then dissolved the residue in ammonium acetate buffer,at last,liquid-liquid partition with dichloromethane;brown rice and hull samples are extracted as soil samples and cleaned-up phase is the same as plant samples.Agilent1100 HPLC,DIAMONSIL-C₁₈ reverse column and mobile phase V（methanol）:V（water）=30:70 were used to analyze.The different fortification levels of soil,rape plant and rape seed are 0.02mg·kg^-1,0.50mg·kg^-1,1.00mg·kg^-1.The average recovery rate of pymetrozine are 82.5%～98.2%,and C.V. are 1.2%～6.3%,respectively.The recovery rates are all exceed 80%and measure up to residual analysis.The LOD（limit of detection） of this method is 0.2ng,and the LOQ（limit of quantification）for sample are 0.0012 mg·kg^-1,0.005 mg·kg^-1,0.003 mg·kg^-1,respectively.Field trial and high-performance liquid chromatography are carried out to study residue dynamics of pymetrozine in soil,seedlings and paddy water.The final residue is in rice and soil also is studied The half-lives of pymetrozine water are 0.19～0.21 days in the paddy field,while,they are 3.5～4.7 days in the paddy soil and 0.51～0.53 days in the paddy seedlings.The degradation rules of pymetrozine in paddy water, soil and seedlings followed the first order chemical reactions dynamics equation.The rice is sprayed one time with 25%pymetrozine WP according to the recommended dosage300g·hm^-2 and high dosage 600g·hm^-2.The final residues of pymetrozine in paddy soil,straw,rice shells and rice are all below the limit of quantification at harvest time.It shows that pymetrozine is a non-persistent pesticide（half-lives<30days）.Recommended dosage300g·hm^-2 of 25%pymetrozine WP is suggested to apply in the rice one time.Based on the experimental results,the MRL of pymetrozine in rice grain may be suggested to be 0.02 mg·kg^-1 temporarily after two-year field trial in Jilin.500W mercury lamp is used to study the photodegradation of pymetrozine.Different concentration and pH of pymetrozine are studied in the same temperature and illumination.In addition,the experiment also analyzed the photodegradation dynamic in soil.After analyzing these samples,we get a conclusion: degradation of low concentration pymetrozine is faster than high concentration;low pH is faster than the high pH;degradation of pymetrozine in 500W irradiation is faster than in sun irradiation.The dynamic equation is C=5.7478e^-0.3887t and the T_1/2 is 1.8h.更多还原